Preparation method of anode material lithium iron (II) phosphate for lithium ion cell

A lithium ferrous phosphate and lithium ion battery technology, which is applied in the direction of battery electrodes, circuits, electrical components, etc., can solve the problems of low specific capacity, impurities or heterogeneous phases in the product, and difficult control of the reaction process, so as to achieve a complete crystal structure, The effect of high chemical purity and easy reaction process

Active Publication Date: 2013-07-03
CHINA AUTOMOTIVE BATTERY RES INST CO LTD
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Problems solved by technology

Literature (Feng Yu, Jingjie Zhanga, Reaction mechanism and electrochemical performance of LiFePO 4 / C cathode materials synthesized by carbothermal method[J].Electrochimica Acta.2009) The analysis of the reaction process during the synthesis of lithium iron phosphate materials also proves this point. Due to the existence of side reactions or competing reactions, the synthesis of phosphite The reaction process is difficult to control when the iron lithium material is used, the batch stability is poor, and the product has impurities or miscellaneous phases, which reduces the electrochemical performance of the material
[0008] PCT / US / 9706671 discloses Li 3 Fe 2 (PO 4 ) 3 It is a lithium intercalation compound, but its discharge platform is lower (2.8v vs Li + / Li), the specific capacity is about 100-120mAh / g, which is difficult to be practically applied in secondary lithium-ion batteries with high specific energy requirements

Method used

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  • Preparation method of anode material lithium iron (II) phosphate for lithium ion cell
  • Preparation method of anode material lithium iron (II) phosphate for lithium ion cell
  • Preparation method of anode material lithium iron (II) phosphate for lithium ion cell

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Experimental program
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Effect test

Embodiment 1

[0036] Lithium carbonate, ferric oxide and ammonium dihydrogen phosphate were prepared according to the Li:Fe:P molar ratio of 3:2:3, and then ball milled in ethanol medium for 100 minutes to obtain a slurry; the slurry was vacuum dried to obtain a precursor , Put the precursor in a pot and put it in a muffle furnace for roasting at a heating rate of 5°C / min, holding at 700°C for 5 hours, and cooling to room temperature with the furnace to obtain Li 3 Fe 2 (PO 4 ) 3 Precursor;

[0037] Will Li 3 Fe 2 (PO 4 ) 3 The precursor and iron powder are ball-milled in ethanol medium at a molar ratio of 1:1 for 30 minutes to obtain a slurry; the slurry is vacuum-dried to obtain a precursor, and the precursor is roasted in a nitrogen-protected vacuum pit furnace and heated The speed is 5°C / min, the temperature is kept at 600°C for 5 hours, and the furnace is cooled to room temperature to obtain lithium iron phosphate material.

[0038] Assemble the simulated battery to the LiFePO prepar...

Embodiment 2

[0043] Lithium hydroxide, ferric nitrate and diammonium hydrogen phosphate are mixed according to the Li:Fe:P molar ratio of 3:2:3, and then ball milled in acetone medium for 12 hours to obtain a slurry; the above slurry is spray-dried to obtain a precursor, Put the precursor bowl into the muffle furnace for roasting, the heating rate is 5℃ / min, the temperature is kept at 900℃ for 3h, and the furnace is cooled to room temperature to obtain Li 3 Fe 2 (PO 4 ) 3 Precursor;

[0044] Will Li 3 Fe 2 (PO 4 ) 3 The precursor and iron powder are ball milled in an aqueous medium at a molar ratio of 1:1 for 12 hours to obtain a slurry; the slurry is spray-dried to obtain a precursor, and the precursor is mixed with nitrogen and hydrogen with a hydrogen content of 5% The mixed atmosphere is placed in a pit furnace for roasting, the heating rate is 5°C / min, the temperature is kept at 600°C for 10 hours, and the furnace is cooled to room temperature to obtain the lithium iron phosphate ma...

Embodiment 3

[0047] The iron oxalate and lithium dihydrogen phosphate are mixed according to the Li:Fe:P molar ratio of 3:2:3, and the slurry is obtained after ball milling in ethanol medium for 24 hours; the above slurry is spray-dried to obtain the precursor, and the precursor is packed The bowl is put into a muffle furnace for roasting, the heating rate is 5℃ / min, the temperature is kept at 800℃ for 15h, and the furnace is cooled to room temperature to obtain Li 3 Fe 2 (PO 4 ) 3 Precursor;

[0048] Will Li 3 Fe 2 (PO 4 ) 3 The precursor and iron powder are ball-milled in acetone medium at a molar ratio of 1:1 for 24 hours to obtain a slurry; the slurry is spray-dried to obtain a precursor, and the precursor is baked in a pit furnace in a nitrogen atmosphere , The heating rate is 5℃ / min, the temperature is kept at 800℃ for 5h, and the furnace is cooled to room temperature to obtain lithium iron phosphate material.

[0049] Assemble the simulated battery to the LiFePO prepared above 4 ...

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Abstract

The invention discloses a preparation method of anode material lithium iron (II) phosphate for a lithium ion cell. The preparation method mainly comprises the following two steps: (1) synthesis of precursor Li3Fe2(PO4)3, blending a lithium source, an iron source and a phosphorus source according to that the molar ratio of Li to Fe to P is 3:2:3, taking deionized water, absolute ethanol or acetone as a medium, ball-milling for 0.5-24 h, drying the obtained slurry, thermally treating for 3-24 hours at the temperature of 500-900 DEG C to obtain the precursor Li3Fe2(PO4)3; and (2) blending the obtained precursor Li3Fe2(PO4)3 and iron powder according to the molar ratio of 1:1, taking deionized water, absolute ethanol or acetone as the medium, ball-milling for 0.5-24 h, drying the obtained slurry, placing the dried slurry into a high-temperature furnace, under the atmosphere of inoxidizability, baking the dried slurry for 5-24 h at the temperature of 500-800 DEG C, and at last preparing the lithium iron (II) phosphate material. By adopting the principle that the lithium iron (II) phosphate material is synthesized by oxidation reduction between zero-valent iron and ferric iron source Li3Fe2(PO4)3 at high temperature, firstly, the pure phase Li3Fe2(PO4)3 intermediate is synthesized in advance, and then reacted with the zero-valent iron to synthesize the lithium iron (II) phosphate, so that the reaction process is easy to control. The synthesized product Li3Fe2(PO4)3 is high in chemical purity, good in electrochemical performance and high in batch stability.

Description

Technical field [0001] The invention belongs to the technical field of energy materials, and relates to a method for preparing lithium iron phosphate, a positive electrode material for lithium ion batteries. Background technique [0002] Lithium-ion batteries have the characteristics of high energy density, long cycle life, low self-discharge, no memory effect, and environmental friendliness. Small lithium-ion batteries have occupied a monopoly position in information terminal products (mobile phones, portable computers, digital cameras) At present, its application fields have expanded from mobile phones and notebooks to power tools, light electric vehicles, hybrid electric vehicles, telecommunications backup power, space and aerospace and other fields, with broad application prospects. [0003] LiFePO 4 It is currently one of the more concerned lithium-ion battery cathode materials. It has the characteristics of high thermal stability, long cycle life, cheap and abundant raw mater...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/58
CPCY02E60/10
Inventor 张向军顾远卢世刚阚素荣
Owner CHINA AUTOMOTIVE BATTERY RES INST CO LTD
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